I've got LEDs in a couple of my old Bally solid state games (GI only, not the controlled lamps). When playing the game there's a bit of a strobe light effect which I assume is due to the GI lighting being AC. Is there any reason sticking a bridge in there and converting the GI to DC wouldn't work? I haven't taken a close look at the GI wiring yet so I don't know if there's anything there that might cause a problem. As a quick test I connected a bridge at the coin door light just to see how much of a voltage drop there would be; 7 volts AC going in was 6 volts DC coming out, so that shouldn't really be an issue. Attached an LED identical to the ones in the game to the bridge and couldn't really tell any difference between it and the other GI lights.